1. Field of the Invention
The present invention relates to the pixel structure of a display device.
2. Description of the Related Art
Organic EL display devices (organic electroluminescent display devices) constitute one-type of an active matrix display device.
If such organic EL display devices are classified according to the relationship between the orientation of the display surface and the surface on which organic EL elements are formed, these display devices can be roughly divided into (1) bottom emission-type display devices in which the back surface side of the surface on which the organic EL elements are formed is used as the front surface, and (2) top emission-type display devices in which the surface on which the organic EL elements are formed is used as the front surface, conversely from the top emission-type display devices.
Top emission-type (TE-type) active matrix (AM) organic EL display devices (OLED) include the display devices disclosed in Japanese Laid-Open Patent Publication Nos. 2007-103098 and 2007-102181 as conventional techniques.
In active matrix organic EL display devices (AM-OLED), active elements are provided on a glass substrate. Pixel electrodes connected to the active elements are provided in a layer above the active elements. A first inter-layer insulating film is disposed between these active elements and the pixel electrodes.
A TE-type AM-OLED using ITO (indium-tin oxide) or metal pixel electrodes on top of a first inter-layer insulating film is disclosed in Japanese Laid-Open Patent Publication No. 2007-103098.
A structure in which an Al reflective films separated for each pixel electrode is provided on top of the first inter-layer insulating film is disclosed in Japanese Laid-Open Patent Publication No. 2007-102181. Moreover, a TE-type AM-OLED in which a silicon-type second inter-layer insulating film composed of silicon dioxide (SiO2) or silicon nitride (SiN) is further provided on top of these reflective films, and pixel electrodes made of ITO are provided on top of the second inter-layer insulating film, is disclosed in this reference.